1. Field of the Invention
The invention relates generally to the field of cooling and heat sinking. More particularly, the invention relates to an integrated liquid cooling system of flexible structure.
2. Discussion of the Related Art
It has been apparent for at least the past 15 years that, as performance improves, there is a growing need for efficient heat dissipation of electronic devices and systems. This trend has remained within the capabilities of air cooling until recently. However, some of today's typical desktop and mobile electronic systems can easily outstrip the cooling capability of existing air cooling techniques. Portable computers have begun challenging traditional thermal management systems.
Air cooling has shown limitations in certain high-power/high-dissipation applications mostly due to the fact that, in a typical situation, heat must be completely removed from an electronic system's enclosure.
On-chip and near-chip refrigeration techniques, such as thermo-electrics, reject a great amount of localized heat, which must also be transported out of the electronic package and its neighborhood. Furthermore, even though air cooling advances will continue to appear, it is known to one skilled in the art that liquid cooling technologies have a much greater capacity (than air cooling technologies) to handle large quantities of heat in small spaces.
A few techniques for integration of liquid cooling with chips have been available since the early 80's. The micro-channel cooling techniques of Tucherman and Pease were shown to be capable of handling high heat flux levels, at least 50 watts per square centimeter at the chip, with only small water flow requirements. Later work has confirmed and reproduced these heat sinks, but commercial applications have not been made. This results from limitations imposed by the integration itself. The micro-channels must be machined in the backside of the wafer or chip to be cooled and the technique does not provide for integrated liquid packaging and delivery systems.
A recent report describes micro-channels formed in aluminum nitride to cool a multichip module (MCM). However, the assembly terminates with conventional tubing fittings at the fluid manifold ends. Thus, using this technique would require the electronic system to include external tubing and pumps.
Heretofore, the mass flow capability of air cooling is incompatible with densely packed or high power dissipation electronics, and the “plumbing requirement” and potential for leaks and spills associated with liquid cooling has restricted its utility.
Another typical problem with liquid cooling technology has been miniaturization. Only one aspect of liquid cooling systems has been miniaturized or integrated to the scale of microelectronics, namely the heat exchanger at a hot chip. The prospect of assembling macro-scale pumps, tubes, and fittings, along with their potential for leaks, has stopped most efforts in liquid cooling technology development. What is needed is an integrated, liquid cooling system with micro-scale components based on flexible circuitry materials technology that solves these problems.
Heretofore, the requirement of providing an integrated liquid cooling system, with micro-scale components based on flexible circuitry materials technology for heat dissipation of high power, densely packaged electronic systems as referred to above have not been fully met. What is needed is a solution that addresses this requirement.